1. Technical Field
The invention relates to inflation devices for use with inflatable balloon catheters, such as are used for interventional medical procedures like percutaneous transluminal angioplasty (PTA) and percutaneous transluminal valvuloplasty (PTV).
2. Description of the Prior Art
Prior to the development of angioplasty or PTA, patients with occluded coronary arteries were primarily treated by arterial or saphenous vein graft bypass operations. The bypass operations involve the suturing of the opposite ends of a segment of a blood vessel, for example either a vein segment removed from a leg of the patient or an artery segment, to opposite sides of the blocked section of the coronary artery. Such operations are costly, require a long patient convalescence period, and involve considerable risk which for many older patients or patients in poor health is likely to result in death.
Angioplasty is now used in place of the bypass operation in many patients, and is used on many patients for whom bypass operations are too risky. During angioplasty, a catheter with a deflated balloon is inserted through arteries to place the deflated balloon in the occluded area. The balloon is then inflated with a solution of sterile contrast media and some other sterile fluid and maintained at several atmospheres of pressure for a brief period to enlarge the artery so as to allow blood flow to return to an acceptable level after the balloon is deflated. Balloon repositioning, inflation, and deflation may be repeated several times to achieve the desired results. The PTA procedure has many advantages over bypass operations in that the procedure does not require invasive surgery, is much less traumatic on the patient, and the recovery period is far shorter.
Similarly, valvuloplasty or PVA has recently been developed as an alternative to valve replacement or valvotomy, both major surgical operations. Valve replacement involves removal of the damaged heart valve and replacement with a porcine valve or an artificial valve. Valvotomy includes surgical cutting of the heart valve to remove or open damaged or stenotic areas.
In valvuloplasty, the balloon on a balloon catheter is expanded in the defective valve in order to enlarge the valve opening. This restores sufficient valve function to return the flow through the valve to an acceptable level. As is angioplasty, the procedure is non-invasive and the patient's recovery period is short when compared to surgical methods.
It is preferable for the inflation device used with a balloon catheter in angioplasty or valvuloplasty to precisely inflate the balloon to a desired pressure, maintain that pressure, and then deflate the balloon to the point of achieving a vacuum, for catheter removal or repositioning. Balloon catheters from different manufacturers and for different procedures require varying pressures. In an emergency situation the inflation device can be rapidly inflated or deflated.
There are several inflation devices commercially available in the prior art. Generally, these inflation devices include a pressure gauge to determine the precise fluid pressure transmitted to the balloon, and employ screw plungers to enable the physician to precisely set the pressure. Quick release levers provide for disengagement of driving thread sector members from the plunger threads to allow rapid plunger movement during inflation or deflation.
Generally, the prior art inflation devices have one or more deficiencies, such as having handles which have a shape and location which make it difficult to simultaneously hold and operate the inflation device, having little or no safety features, having hidden fluid pressure chamber regions or passageways allowing undetected air bubbles to be trapped where they interfere with pressurization or pose a threat in the event of balloon failure, and/or other deficiencies.